Cold Chain Transportation Fuel Level Monitoring Solution: A vehicle that can run isn’t necessarily safe; only when the refrigeration unit has sufficient oil can it maintain continuous cooling.

The biggest difference between a refrigerated truck and a regular truck isn’t just the addition of a refrigeration unit in the cargo area.

Many cold chain vehicles have two relatively independent fuel systems: one for the vehicle chassis and another for the independent refrigeration unit; in some models, the refrigeration equipment is powered by a PTO (power take-off). A driver might see that the main fuel tank still has fuel and assume everything is fine, but the refrigeration unit’s fuel tank could already be nearly empty. While the vehicle continues to run, the refrigeration unit could stop at any moment, actually putting the cargo at greater risk.

For temperature-sensitive goods such as fresh produce, frozen foods, vaccines, and pharmaceuticals, a loss of refrigeration is not merely an equipment issue—it affects the value of the entire shipment, delivery reliability, and the risk of claims.

FOFN’s cold chain transportation fuel monitoring solution enables fleets to simultaneously determine whether a vehicle is “roadworthy” and whether the refrigeration unit can “continue operating” through integrated management of the chassis fuel tank, refrigeration unit fuel tank, cargo compartment temperature, GPS location, and refrigeration unit operating status.

In this document, “refrigeration fuel consumption” refers to the consumption of diesel or other fuels used by the refrigeration unit, not compressor lubricating oil. Since refrigeration unit brands, standalone units, and PTO drive configurations vary, you must verify the vehicle’s actual configuration and the available operational signals before installation.

Applicable Scenarios

This solution is applicable to:

• Cold Chain Logistics Fleet
• Fresh Produce Delivery Vehicles
• Frozen Food and Dairy Product Distribution
• Pharmaceutical Cold Chain and Vaccine Transportation
• Cross-border Cold Chain Transportation
• Delivery from cold storage to retail locations, and from warehouse to warehouse
• Refrigerated trucks equipped with fuel tanks and independent refrigeration units
• PTO-powered temperature-controlled vehicles for refrigeration equipment

Why Is Managing Fuel for Refrigerated Trucks More Challenging Than for Regular Trucks?

Chassis oil and refrigeration unit fuel are two separate accounts.

The fuel tank for the refrigerated truck’s engine ensures the vehicle runs, while the fuel tank for the refrigeration unit ensures the refrigeration system operates. The two fuel tanks serve different purposes and have different consumption patterns.

Just because the oil level in a vehicle’s chassis is normal does not mean the refrigeration oil level is normal; if the refrigeration oil tank is not refilled in a timely manner, the vehicle can still continue to operate, but the temperature inside the cargo compartment may quickly spiral out of control.

Refrigeration energy consumption is often overlooked

Many fleets only track total refueling costs for their vehicles without separating fuel consumption for driving from fuel consumption for refrigeration. As a result, it is difficult to analyze which refrigeration units are inefficient, which vehicles idle for extended periods while running the air conditioning, or which routes result in high fuel consumption due to refrigeration.

Temperature alarms and fuel level alarms are often two separate systems.

Looking at temperature alone, you only know that the cargo compartment temperature has risen; looking at fuel level alone, you only know that the fuel tank is getting emptier. The real value lies in combining temperature, refrigeration unit operating status, and fuel data to determine whether temperature anomalies are related to low refrigerant levels, unit shutdown, or abnormal operation.

Long-distance and cross-border transportation, where refueling en route is inconvenient

When refrigerated trucks travel long distances, cross-border routes, or to remote areas, it may not always be convenient to refuel the refrigeration unit. Without advance warning of low fuel levels, drivers may not have enough time to arrange for a refueling stop by the time they notice the issue.

What parts make up the proposal?

1. Independent monitoring of the chassis fuel tank

The underbody fuel tank is used for vehicle operation. Once a fuel level sensor is installed, the platform can display the vehicle’s remaining fuel level, fuel consumption during operation, refueling records, and instances of abnormal fuel loss.

Key Points:

• Remaining Fuel Level in the Vehicle's Main Fuel Tank
• Normal fuel consumption during driving
• Refueling time, location, and amount
• Abnormal Fuel Level Decreases During Parking or Non-Operational Periods
• Refuueling Arrangements for Long-Distance Routes

2. Independent Monitoring of Refrigeration Unit Fuel Tanks

For refrigerated trucks equipped with a fuel tank for the independent refrigeration unit, fuel level monitoring devices can be installed separately. The platform displays the refrigeration unit’s fuel level and the chassis’s fuel level separately to prevent the two sets of data from being mixed together.

Administrators can view:

• Current fuel level in the refrigeration unit’s fuel tank
• Trends in Refrigeration Unit Fuel Consumption
• Low Fuel Level Alert for Refrigeration Systems
• Refrigeration Unit Oil Refill Record
• Abnormal Fuel Loss During Non-Operating Hours
• Comparison of Refrigeration Fuel Consumption Among Different Vehicles

This way, you can know in advance which vehicle needs to have cold-start diesel refilled, rather than waiting until the engine has stopped running to find out.

3. Cargo Compartment Temperature Monitoring

Install temperature sensors inside the refrigerated cargo compartment and set different temperature ranges based on the type of cargo.

For example:

• Frozen foods typically require a low-temperature environment;
• Fresh produce and dairy products are more sensitive to temperature fluctuations;
• The pharmaceutical cold chain may require stricter temperature logging and alert rules.

The platform can record temperature curves, duration of temperature deviations, alarm events, and recovery times, providing traceable data for the cargo transportation process.

4. Collection of Refrigeration Unit Operating Status Data

Depending on the vehicle and refrigeration unit conditions, the system can collect or determine the refrigeration unit's operating time, ignition status, PTO status, or related operating signals.

Combining operating status with refrigeration fuel consumption can help analyze:

• Is the cold engine operating normally when it should be running?;
• Is fuel consumption noticeably higher when the engine is running cold?;
• The unit has been running for a long time, but the temperature has not dropped;
• Is the air conditioning left running for extended periods when the vehicle is parked?
• After the chiller stops, does the temperature begin to rise abnormally?

5. GPS Tracking and Route Management

GPS terminals record vehicle locations, routes, dwell times, and arrival times at customer locations. Managers can analyze routes, temperature data, and fuel levels to determine whether any abnormalities occurred during the transport of cold-chain vehicles.

For example, if a vehicle remains at an unplanned location for an extended period while the refrigeration unit’s fuel level drops rapidly or the temperature begins to fluctuate, priority should be given to verifying the situation on-site.

How do I set up the interlock between dual fuel tanks, temperature, and cold engine operation?

The key to cold-chain vehicles is not looking at individual data points, but rather determining whether the data points match.

Under normal circumstances

While the vehicle is operating normally, the chassis fuel level gradually decreases; when the refrigeration unit is running, the refrigeration fuel level also decreases slowly; the cargo compartment temperature remains within the set range. This is a relatively healthy operating record.

Situations to Watch For

• Main fuel tank is normal; refrigeration oil tank is below the threshold.
  The vehicle can continue running, but the engine may stall due to low fuel levels; refueling should be arranged as soon as possible.
• The refrigeration unit is continuously consuming fuel, but the cargo compartment temperature is not dropping.
  You may need to check the unit’s operating status when cold, its cooling performance, the door seals, or the location of the temperature sensors.
• After the refrigeration unit stops running, the temperature inside the cargo compartment continues to rise.
  In such situations, drivers and dispatchers must be notified promptly to prevent cargo from being exposed to excessive temperatures for extended periods.
• The vehicle is parked and the engine is not running, but the refrigerant level in the tank has dropped significantly.
  Verify whether there are any instances of abnormal fuel withdrawal, fuel transfer, or sensor fluctuations by cross-referencing time, location, and on-site operations.
• On cross-border or long-haul routes, refrigerant fuel consumption exceeds expectations.
  You can adjust the refueling schedule in advance to avoid running out of fuel while on the road.

How can we implement refined management of cold chain costs?

Many fleet operators know that a refrigerated truck “uses a lot of fuel,” but they don’t know whether it’s the chassis or the refrigeration unit that’s causing the high fuel consumption.

After managing the two fuel tanks independently, you can track the following separately:

• Chassis fuel consumption per 100 kilometers
• Hourly fuel consumption for refrigeration
• Refrigeration fuel costs per shipment
• Differences in Cold-Start Fuel Consumption Across Seasons
• Cost Differences by Vehicle Model, Route, and Cargo Temperature Zone
• Refrigeration Energy Consumption During Parking and Unloading

This data helps fleets more accurately assess transportation costs. In particular, during high summer temperatures, long wait times for unloading, or cross-border queues, the proportion of fuel used for refrigeration may increase significantly.

Value of the Solution

Ensure the chiller does not run out of fuel, thereby reducing the risk of shutdown.

When the fuel level in a refrigeration unit falls below the set threshold, the platform issues an early alert, giving dispatchers and drivers time to arrange for a refueling and preventing the refrigeration unit from shutting down due to low fuel during transport.

Chassis oil and refrigeration oil are managed separately.

By tracking vehicle fuel consumption and refrigeration fuel consumption separately, the cost structure becomes clearer, and it is easier to identify anomalies.

Temperature, fuel level, and operating status trigger linked alerts

Events such as temperature thresholds being exceeded, cold engine shutdowns, and low refrigerant oil levels can be viewed in context. This makes it easier for managers to identify the source of the problem without having to repeatedly cross-check multiple systems.

Provide process documentation to ensure cargo security and customer delivery

Temperature curves, routes, parking times, engine-off status, and fuel level records can be compiled into comprehensive transportation data, providing a reference for internal reviews and client communications.

Suitable for long-haul, cross-border, and multi-temperature-zone delivery

For cold-chain transportation involving long distances, few refueling stops, and high-value cargo, identifying risks related to refrigeration fuel in advance is more important than dealing with them after the fact.

Recommended Deployment Methods

We recommend selecting a few typical refrigerated trucks for a trial run:

• 1–2 refrigerated trucks with fuel tanks equipped with independent refrigeration units
• 1 PTO-driven refrigerated vehicle
• 1 long-haul or cross-border cold chain route
• 1 intra-city multi-stop delivery route

First, complete the calibration of the main fuel tank and refrigeration oil tank, confirm the temperature measurement points in the cargo compartment, set the low-fuel-level threshold, and configure the temperature alarm rules. After the system has been running for a period of time, adjust the warning rules based on the vehicle’s actual fuel consumption and seasonal variations.

Frequently Asked Questions

Why do refrigerated trucks need to monitor two fuel tanks?

This is because the chassis fuel tank powers the vehicle’s operation, while the refrigeration unit’s fuel tank powers the refrigeration unit itself. The presence of fuel in the main tank does not necessarily mean the refrigeration unit still has fuel; independent monitoring of the two fuel tanks prevents situations where “the vehicle can still run, but the refrigeration unit has to shut down.”

Can PTO-driven refrigeration units also perform fuel consumption analysis?

Yes, but the analysis method differs from that used for standalone fuel-powered refrigeration units. PTO refrigeration units are typically linked to the engine’s operating status, so a determination must be made by combining vehicle ignition status, PTO signals, operating hours, and main fuel tank consumption data. The specific data retrieval method must be confirmed based on the vehicle model and refrigeration unit.

Does an abnormal temperature always mean the chiller is low on oil?

Not necessarily. Temperature anomalies may also be related to frequent opening of vehicle doors, refrigeration unit malfunctions, cargo loading methods, cargo compartment sealing, ambient temperature, or sensor mounting locations. The value of the system lies in integrating temperature, fuel level, and refrigeration unit operating status to help quickly pinpoint the cause of the issue.

At what fuel level should an alarm be triggered for a refrigeration unit?

There is no single value that applies to all vehicles. We recommend setting these parameters based on fuel tank capacity, fuel consumption per hour when the engine is cold, current ambient temperature, remaining distance, and the distance that can be covered with the remaining fuel. For long-distance or cross-border transport, you may set earlier warning thresholds.

Can the system be used for the pharmaceutical cold chain?

It can be used to provide process data such as temperature, location, fuel level, and operational status. If the transported pharmaceuticals are subject to regulatory, validation, or specific temperature-controlled recording requirements, sensor accuracy, recording frequency, data retention, and validation procedures must also be confirmed in accordance with local pharmaceutical cold chain regulations.

Will temperature and fuel level data be lost if the internet connection is unstable?

Local data storage and resynchronization after network recovery can be configured based on the device model. The specific retention period and upload frequency must be determined based on the device model, communication network, and project requirements.